The present invention relates to novel xanthine compounds having a diuretic effect, a renal-protecting effect and a bronchodilatory effect.
Heretofore, theophylline, i.e., 1,3-dimethylxanthine has been known as a diuretic, a vasodilator, etc. [The Merck Index, 10th edition, 9110 (1983)].
Xanthine compounds carrying, at the 8-position thereof, substituents such as alkyl, alicyclic alkyl, aralkyl, aryl, etc. have a diuretic effect, as disclosed in East German Patent No. 31,772 [Chem. Abst., 63, 18120d (1965)]and West German Patent No. 1,245,969 [Chem. Abst., 67, 90994n (1967)].
In relation to the compounds of the present invention, 8-(1-adamantyl)-1,3,7-trimethylxanthine is described in Tetrahedron Lett., 27, 6337 (1986). However, nothing is mentioned on its pharmacological effect. Further, 8-(1-adamantyl)-1,3-dipropylxanthine having an activity of antagonizing adenosine A.sub.1 receptor is described in J. Med. Chem., 33, 1906 (1990).
The object of the present invention is to provide novel xanthine compounds exhibiting strong diuretic and renal-protecting effect, based on the finding that xanthine compounds which are adenosine receptor antagonists, particularly those having an activity of selectively antagonizing adenosine Al receptor, have strong diuretic and renal-protecting effect.